GB1356247A - Silica-gels - Google Patents

Abstract

1356247 Silica gel ZIRCONAL PROCESSES Ltd 21 Oct 1971 [5 Nov 1970] 52693/70 Headings C1A and C1J A silica gel is prepared by alkaline gelation of either an acid silica aquasol, an acid silica alcohol or an acid hydrolysate of an organic silicate with a dispersion of magnesium oxide in a mixture of water and a totally water miscible polyhydric alcohol. The term "silica gel" includes co-gels of silica with one or more metal oxides; and the term "acid hydrolysate of an organic silicate" includes mixed acid hydrolysates or organic silicates and metal salts. The dispersion was used for gelling a hydrolysate prepared from AlCl 3 , ethyl alcohol and ethyl silicate in Examples I and III, an acid hydrolysate prepared from ethyl silicate, hydrochloric acid and ethyl alcohol in Examples II and IV, a silica sol. in Examples V and VI and a silica alcosol in Example VII. Refractory articles where the silica gel acts as a binder for aluminium oxide (see Example II), aluminium silicate, aluminosilicate, magnesium oxide, magnesium silicate, zirconium oxide, zircon, crystalline silicon oxide, silicon carbide and spinel may be made by mixing the refractory material with the silica aquasol or alcosol or acid hydrolysate and the above gelling medium into a slurry, forming the slurry into the desired shape, drying and firing.